A far-right contender has advanced to Portugal’s presidential run-off for the first time, challenging mainstream parties and the right-wing minority government of Prime Minister Luis Montenegro.

Socialist Antonio Jose Seguro led Sunday’s first round with 31.1 percent, while Chega party candidate Andre Ventura trailed with 23.5 percent, ahead of liberal Joao Cotrim Figueiredo and government-backed Luis Marques Mendes. No candidate won outright, the first time in four decades.

Sunday’s result marked "another step forward for the electoral and political growth of the radical right," said Antonio Costa Pinto of the University of Lisbon. "What matters now is what level of hegemony Ventura will achieve on the right, depending on his election results… That represents a major problem for a minority government which must negotiate with Andre Ventura in order to survive."

Montenegro did not guide conservatives on whom to support. "This may serve him in the short term, in order not to alienate Andre Ventura's voters, but the lack of demarcation may ultimately penalise him electorally," said political scientist Paula Espirito Santo.

Even without a first-round win, Ventura scored "a major victory, insofar as he has overtaken the traditional right-wing parties and confirmed his status as leader of the opposition," she added. Chega became the biggest opposition party in May 2025, winning 22.8 percent of the vote and 60 seats.

While Seguro is the favorite, Costa Pinto warned, "He is the probable next president -- but he will have to mobilise more voters." Ventura, he said, will try to "polarise" the contest and "blackmail" other right leaders by portraying them as responsible if the left wins.

National daily Publico called the run-off a clash "between moderation and radicalism" in an increasingly fragmented political landscape.